The reason is really rather easy, and better to show than commonly explain more readily those with PTSD tend to get mad quicker, and faster than others at small dumb things.
I would like to explain this, and you will better understand the difference to those with PTSD, and those without.
Whether you realise it or not believe it, everybody has this thing called "good stress" in their life, which consists of such matters as getting PTSD stressors represented out of bed, day to day tasks, going to work, cooking dinner, etc etc. No problems with that one.
The obvious, when something bad happens, or is really hindering you, is normally classified as "bad stress", which consists such matters as paying invoices, cash, relationships, getting fired from your job, etc etc etc. Terrible anxiety is got by everybody at some stage within their day; it only depends on the sum, and the individual themself.
As it is possible to see, a standard man is represented by Cup 2, and with both bad and good anxiety. They still have lots of room in their cup without overflowing (exploding, rage, wrath, etc etc). Before being pushed on the edge a regular person has the ability to take a lot of stress within their everyday life.
Now whilst we still have both positive and negative stress, there's now this thing called "PTSD" in our cup. The problem with that is that we still possess the same amount of good and poor stress as everyone else, though we also stress cup have this huge chunk of PTSD which includes more and our injuries.
As you can view from this cup, with good anxiety and PTSD, you actually don't have much room for anything else. A little "bad stress" to get a person with PTSD, plus they overflow fairly rapidly compared to anyone else.